Method of joining fluid filled electric cables



L. EMANUELI Aug. 4, 1936.

METHOD OF JOINING FLUID FILLED ELECTRIC CABLES Original Filed Oct. 30, 1930 2 Sheets-Sheet l NVENTR d. fla/(maa,

' ATTORNEYS Aug. 4, 1936. L. EMANUELI METHOD VOF' JOINING' FLUID FILLED ELECTRIC CABLES Original Filed Oct. 30, 1930 2 Sheets-Sheet 2 rW//a A TTORNE Y IN VEN TQR n .N/Effw BY sm,

Patented Aug. 4, 1936 METHOD F JOINING FLUID FILLED ELECTRIC CABLES Luigi Emanueli, Milan, Italy, assignor to S. I. Pirelli, a corporation of Italy Original application October 30, 1930, Serial No. 492,343, Patent No. 1,979,149. Divided and this application March 23, 1934, Serial No. 717,121. In Canada. and South Africa July 15,

The present invention is directed to an improved method of joining high tension iiuid lled electric cables.

This application is a division of application Serial No. 492,343, led October 30, 1930, which on October 30, 1934 matured into Patent No. 1,979,149, and in which an improvement is disclosed and claimed over my former U. S. Patent 1,698,051, issued January 8, 1929. While the invention claimed in my said Patent No. 1,979,149, above referred to, is directed to the structure of an improved joint for connecting high tension fluid filled electric cables, the present invention disclosed and claimed herein is directed to the l5 improved method of joining cables of this type and to the method of assembling my improved joint. Prior to the ling of the above mentioned parent application, it was the practice to ship cable which had been filled with oil from the factory to the point of installation, the ends of said cable being suitably sealed during transit to prevent escape of oil. It also had been the practice to make the joints in the eld wherever required, usually in manholes below the surface of the streets where the working conditions were extremely unfavorable due to lack of space, and due to dirt and moisture. In addition, the jointer had to contend with a certain although limited amount of oil which escaped from the conductor ends during the splicing or joining operation.

It is an object of this invention to provide an improved method of joining the ends of these high tension fluid lled electric cables which f will reduce to a minimum the amount of work which the jointer has to do in the field.

It is a further object of the invention to provide a method for joining these cables where the more diflicult operations of making the. joint o such as the placement of insulation therearound and the lling of the casing with degasied oil may be done in the factory where the conditions i are favorable to good workmanship and where close inspection by competent persons is avail- 45 able at all steps in the manufacture.

It is a still further object of the invention to provide a method of joining these cable ends which will permit the manufacture of the joint,

its wrapping with insulation and filling with a 50 permanent charge of degasied oil at the factory and hence relieve the necessity for performing this delicate operation atthe point'Y of in stallation.

Numerous other and further objects of the 55 invention will Ibe apparent from a consideration 5 Claims. (Cl. 173-268) of the following specification when taken in connection with the accompanying drawings.

In' the drawings which are illustrative of my invention,

Fig. 1 is a view of a stop joint in elevation; 5

Fig. 2 is a part sectional and part elevational View of the left end of the joint of Fig. 1;

Fig. 3 is a sectional view of the mid-section of the joint of Fig. 1 with the outside casing omitted; l0

Fig. 4 is a cross sectional view taken on line 4-4 of Fig. 3; and

Fig. 5 is a sectional view of one end of the cable section or reel length and illustrates the part of the joint which is made in the eld. l5

It is to be understood that stop joints -are special joints used for interrupting the flow of oil or other insulating liquid between two adjacent sections of a iluid filled cable, while the electrical connection between the sections is maintained.

As indicated above, my improved joint comprises two distinct parts, i. e., y.the part which is prepared in the factory which is-the principal part andwhich is later shipped with its contents intact to the point of installation, and the minor part which is prepared by the jointer in the eld.

The part .which is prepared in the factory comprises a cylindrical outer casing I in the form of a tube, a cylindrical element 5y of reduced diameter which is suitably jointed to the tube I by means of a conical portion 2, and an element 3 comprising a conical portion and a cylindri- Y cal portion of still smaller diameter which element 3 is suitably jointed to the element 5. The various parts of the casing are telescopically arranged and may be joined by wiped soldered joints. The opposite end of the casing is similarly constructed.

Inside of the casing are two duplicate insulators 4 made of porcelain or equivalent material, said insulators being of tubular form and gradually tapering from the outer to the inner end, there being a small clearance between the inner wall thereof and the insulation on the encased conductor. For simplicity only one of these in- .sulators is shown but it is to be understood that both are alike and are supported in the same manner and having the same axis.

The'large end of the insulator is supported in a metal cap which comprises a head 6 and a bell-shaped portion 'l which ts the inner wall of the part 5 of the casing and is held in place by Screws 8 which are subsequently covered with 55 contact caps so that said parts have the samesolder to seal the joints. The head makes a good iit with the inner wall of a cylindrical portion oi the casing part il and is soldered 'thereto to seal the joint. lt will be observed that the parts il and 5 of the Acasing are in telescopic relation which serves to stiien the casing in the region of the head. The cap is' supported at both ends, by the head at one end and the haring end l! at the other. As a result the insulator is freed of any casing strains. The cap and insulator are united by a body of cement 9. Et is desinable to provide a gasket between the insulator and the cap to prevent direct contact between them.

The inner end of the insulator is also provided with a metal cap l@ which to distinguish it from the other cap and also to designate its purpose will be termed a contact cap. This cap has a socket at one end to receive the inner end of the insulator` and the two parts are united by a body of cement lll. By dispensing with anges on the insulators and making them of tubular orrn the danger of breaking or cracking both in the manufacture or the insulator and in the assembly is greatly reduced. The cap has a closed inner end and also a cylindrical bore or socket to receive the inner end ci the contact making parts which are aixed to the cable end. The closed ends or heads of the opposed contact caps are united by bent strips of copper or equivalent material l2 which are fastened in place by screws t3. These strips electrically connect the caps and also form a ilem'ble coupling which will take care of contraction and `expansion of the conductors in the direction ot their length and also reduce to a minimum the strains which would be occasioned by any lack of alignment of the two insulators d and their caps. It is oi paramount importance to prevent cracking of the porcelain insulators during manufacture and assembly both in the factory and in the field.

In order to obtain a suitable distribution of the electric field about the contact caps and coupling, a metal shell or shield le is provided which surrounds them. It has inturned ends which cover the outer ends of the caps and closely surround and are supported by the porcelain insulators. Because of its shape the shell in order to be assembled has to be divided and in this instance it is divided longitudinally into two equal parts, as shown in Fig. 4, and the joint between the parts is soldered or otherwise made. Prior to uniting the halves of the shell a exible conductor le is secured at one end to the shell and the other end to one of the potential. The shell and adjacent ends of the insulators are covered with numerous layers of paper lt or other insulating material, which layers are applied longitudinally so that the electrical forces will be perpendicular to the surface of the paper. In applying the paper, suitable binding material is used, for example a silk thread is wrapped thereon between every three or four layers.

As the diameter oi the shell tl is larger than that of the inner ends of the insulators ll, a second body of insulation ll is provided at each end of the shell which covers a 'part of the insulators and also the ends of the insulation lb. 1t is made of folded-over paper tape which is held in place by any suitable binding means. Over the insulaticns thus applied is a third body of insulation it. made of impregnated cable accuses paper. ln forming this body a width of paper is selected which is great enough to cover the central body and all or practically all of the end bodies of applied insulation. When finished the outer body forms a tube, and the layers are prevented from loosening by means oi any suitable binding material.

In assembling the parts of the joint thus far described the inner parts are first prepared and insulated, after which the casing parts are slipped endwise into place and properly united to form a hermetically sealed casing. The easing is then evacuated and for this purpose the ntf ting 2li is employed. After being evacuated the casing is lled with degasied oil and sealed at the fitting Eil, after which the joint is ready to be sent to the place oi' installation. in this connection, particular attention is called to the fact that the jointer in completing the joint in no way disturbs the casing or its contents, all necessary work thereon having been done at the factory. Due to this much time and labor are saved in the held and elaborate evacuating and filling operations are avoided.

In Fig. 5 are illustrated the parts which are assembled in the field using tor the purpose certain metal; parts which are made at the factory. Each connector comprises a relatively long sleeve having asocket 2l at one end to receive the strands 22 of the conductor after the insulation 23 thereof has been removed in a series of steps. Inside the conductors and resting on an internal shoulder in the socket is a flanged metal sleeve 2d, one end of which engages the spirally wound metal core 25 over which the conductors are stranded. The core of the cable when installed is lled with degasied oil or other liquid insulation and since it is ,dimcult to make a soldered joint under these conditions a vice or other mechanical device is employed to squeeze the wall of the socket about the conductor strands, the sleeve 2Q serving to withstand the pressure so exerted. Each connector also has a tubular extension 25a of smaller diameter than the socket and contains ports 2b through which oil is free to :dow from the cable core into and through the small annular space between the conductor covering and the inner Wall of the porcelain insulator. ln the socket portion of the connector is a small chamber 2l which contains oil received from the cable core. The opening from the chamber to the tube 25a is controlled by a small valve or stopper 28 to which is attached a thread or strlng' for seating it. This valve is seatedv when the socket is applied to the condutcor end so as to prevent the escape of oil from the conductor core and remains in this position until the work of assembling is completed. The string is broken before the cable end is inserted in the factory made joint. During the period of time required to strip the conductor of its lead sheath and insulation preparatory to applying the connector a limited amount of oil will escape from the core which serves to prevent the entrance into the cable 'of air and moisture. The amount of oil which escapes will be largely governed by the pressure exerted by the reservoir at the end of the cable away from the place where the joint is being madef Surrounding the tube 25a and spaced therefrom is a series ofindividually movable contact bars 29 which are loosely held at one end by a band or ring 3Q and at the other end by a disk 3l which is screw threaded on the end of the tube and has a groove 32 to receive the notched ends of the bars. A steel spring 33 is located between each pair of bars and exerts pressure therein tangentially. Since the bars are radially disposed about a common centerthese springs press them outwardly, the band or ring 30 limiting their outward movement at one end while the groove 32 acts as a pivot for each of the bars. The bars are individually connected to the base of the socket by flexible copper connectors 34 which permits each bar to properly seat or engage with the wall or bore of the contact cap and because of the resiliency of the structure as a whole this will take place without imposing any undue strains on the cap and hence on the porcelain insulator.

After the mechanical parts are assembled the wall of the socket and adjacent stepped insulation 23 are covered with a body of insulation, such as varnished tape 35 for example. The cable end is then covered with insulation 36 for example of paper tape to the desired thickness. After this the electrostatic controls 31, Fig. 2, are mounted in place. These controls are made of two pieces of metal united by anges and screws and are ared to fit over the insulation 36.

Having prepared the cable ends, the next step is to slip them into place in open ends of the factory prepared part of the joint, after which the thimbles 33 which have previously been slipped over the cable ends are connected to the casing and to the lead sheath`39 of the cable by wiped soldered joints 40. To some part of the casing on the cable side of the head is attached a fitting M by which this part of the casing is first evacuated and later filled with degasied oil and through which oil may be admitted to and received from the cable as its temperature changes, a suitable reservoir being used for the purpose. This treatment has to be followed for both ends of the joint.

As has been previously stated the valves 28 are seated and hence oil from the core cannot flow from the core through the clearance space between the porcelain insulator and the cable into the chamber 42 as is necessary. To unseat the Valves, which seal the cable sections against loss of oil, it being remembered that the casing in all its parts is completely filled with oil, pressure is applied to the oil in the chamber 62 through the fitting lll, as by a pressure pump for example, to a value suiciently in excess of that in the cable core to unseat the valves 28 and permit them to fall into the chambers 2l where they no longer obstruct the ow of oil to and from the cable core. The pump is then removed and the usual connection made between the fitting and a reservoir of suitable character. When the seals are broken oil from the cable is in free communication with those spaces beyond or outside of the insulators, for example those defined by parts 3 of the casing.

In the part 2 of the casing which is in the joint side of the head or partition 8 which divides the same into two chambers, is a fitting i3 which ordinarily is not in use but which may be used in case of oil leakage in a cable section beyond to supply oil to said section. This may be done by connecting both fittings il and i3 to an oil reservoir. Under these conditions, the joint is temporarily ineffective as a stop joint but will nevertheless supply oil to take care of leakage until a repair can be made after which the fitting 43 will be sealed -or plugged.

Instead of a separate fitting 43, the fitting 20 may be employed if desired.

It may also be pointed out that the valves 28 will remain closed during the period that the chamber 42 and the spaces communicating therewith are being evacuated and hence there is no danger of the vacuum pump withdrawing oil from the cable.

From the foregoing it will be seen that the casing and its contained parts are constructed to be shipped to the customer as a unitary structure, in other words, as an article of manufacture. In some instances these joint casing parts will be shipped for use with cable and terminal parts for a new installation and in others as repair or replacement parts. It is .evident that modifications may be made in the particular form of the contact devices located within the contact caps without requiring changes in the casing and its parts.

It will be seen that by reason of my improved construction the casing and its parts may be -made at the factory where the conditions of manufacture are most favorable, that the interior of the casing is evacuated and filled with oil so that no air or moisture can enter, and that so far as this part of the joint is concerned the jointer takes no part it its manufacture and does not have to disturb it in any way in making a joint all of which results in a bette and cheaper final product.

What I claim is:

1. TheI method of joining sections of a high tension fluid filled electric cable, said cable sections each having a conductor surrounded by a metallic sheath, which method comprises permanently assembling parts of a joint within a casing, said joint having externally accessible sockets, each socket being adapted to receive one end of the conductor of its respective section, evacuating the casing and filling it with insulating uid, shipping the casing with its contents intact to the point of installation, preparing the ends of the cable sections to be joined, inserting the ends of the conductors into their respective sockets in said joint, uniting the cable sheathing of l each section to the joint casing to form chambers one surrounding each socket and the end of the cable section inserted therein, filling each chamber with insulating fluid and releasing the fluid within each cable section to communicate with the fluid in its respective chamber.

2. The method of joining sections of a high tension fluid lled electric cable, said cable sections each having a conductor surrounded by a metallic sheath, which comprises permanently assembling parts of a joint within a casing, said joint being provided with cavities forming externally accessibe sockets, evacuating the casing and filling it with insulating iiuid, shipping the casing with its contents intact to the point of installation, preparing the ends of the cable sections to be joined, inserting the ends of the conductors into their respective' sockets in said joint, uniting the ends of the joint casing to the adjacent sheathing of each cable section to form chambers one surrounding each socket and the end of the cable section inserted therein, lling each chamber with insulating fluid and establishing communication between the interior of each cable section and the space around its end within its respective chamber.

3. The method of joining sections of a high tension fluid filled electric cable, each of said cablev sections having a conductor surrounded by a metallic sheath, which rnethod comprises permanently assembling parts of a joint Within a casing, said joint being provided with cavities forming externally accessible sockets, evacuating the casing and lling it With insulating iuid, shipping the casing with its contents intact to the point of installation, preparing the ends of the cable sections to be joined, inserting the ends of the conductors into their respective sockets in said joint without disturbing the contents of said casing, uniting the joint casing to the adjacent sheathing of each cable section to form chambers one surrounding each socket and the ends of the cable sections inserted therein, filling each chamber with a body of insulating uid and releasing the iiuid within each cable section to communicate With the fluid within its respective chamber surrounding its end.

4. The method of joining a pair o sections of high tension uid iilled electric cables, each of said cable sections having a conductor surrounded by a metallic sheath, which method comprises permanently assembling parts of a joint within a casing, said joint being provided with cavities forming externally accessible sockets, evacuating the casing and filling it with insulating iiuid, shipping the casing with its contents intact to the point of installation, the ends of the cable sections to be joined being provided with valves, said valves being maintained against their seats by the pressure of accese@ the uid within the cable sections, inserting the ends of the conductors into their respective sockets in said joint, uniting the casing of said joint to the sheathing of each adjacent cable section to form a pair of chambers, iilling the space Within each such chamber and around said cable ends with insulating uid, and inomentarily increasing the pressure thereoi 'subciently to unseat said valves.

5. The method of joining a pair of sections of high tension iuid lled electric cables, each of said cable sections having a conductor surrounded by a metallic sheath, which. method comprises permanently assembling parts of a joint within a casing, said joint being provided with cavities forming externally accessible societs, evacuating the casing and iilling it with insulating fluid, shipping the casing with its contents intact to the point of installation, the ends of the cable sections to be joined being provided with valves, said valves being rnaintained closed by the pressure of the fluid Within the rcable sections, inserting the ends of the conductors into their respective sockets in said joint, uniting the casing of said joint to the sheathing of the adjacent cable sections to rorm closed chambers, filling the spaces within such chambers and around said cable ends with insulating fluid, and finally opening said valves so as to establish communication between such spaces and the interiors of the cable sections.

LUrGr EMaNUnLr. 

